Machines for compression molding closure shells, or compression molding sealing liners within closure shells, typically include a turret or carousel that rotates around a vertical axis. A plurality of molds are provided around the periphery of the carousel, in the form of male and female mold sections that are aligned along vertical axes parallel to the axis of rotation. Cams drive one or both of the mold sections of each pair between an open position, in which a molded part is stripped from the mold and a charge of molten plastic material is placed into the mold, and a closed position in which the mold sections are brought together to compression mold the shell or liner. In a liner machine, premade shells are placed in a nest when the mold sections are open, and a charge or pellet of liner material is placed within the mold before the mold is closed. U.S. patents that illustrate machines of this type for compression molding plastic closure shells include U.S. Pat. Nos. 5,670,110, 5,989,007, 6,074,583 and 6,478,568. U.S. patents that illustrate machines of this type for compression molding sealing liners within closure shells include U.S. Pat. No. 5,451,360.
U.S. patent document 2006/0233904A1 discloses a vertical wheel compression molding machine that rotates around a horizontal axis for compression molding closure shells or sealing liners within closure shells. The apparatus for delivering mold charges to the compression mold cavities includes a carrier plate mounted for rotation around a vertical axis and diametrically spaced mold charge placement mechanisms carried by the plate. Each placement mechanism includes a rotatable shaft having a gear at one end coupled to a gear disposed in (adjustable) fixed position adjacent to the plate. The opposing end of each shaft carries a pick-up cup for receiving a mold charge and transporting the mold charge to a mold cavity on the wheel.
The present disclosure involves a number of aspects that can be implemented separately from or in combination with each other.
An apparatus for placing a mold charge into a mold of a compression molding machine, in accordance with one aspect of the present disclosure, includes a carrier mounted for rotation around a first axis, at least one arm mounted on the carrier for rotation around a second axis at an angle to the first axis, and a mold charge pick-up cup on the arm for receiving a mold charge from a nozzle, transporting the mold charge and placing the mold charge into a mold of the compression molding machine. A cam is carried in stationary position adjacent to the carrier surrounding the first axis, and a cam follower is operatively coupled to the arm in engagement with the cam for rotating the arm and the mold charge pick-up cup around the second axis as the carrier is rotated around the first axis. In exemplary embodiments of the disclosure, the cam follower is directly coupled to the arm, or is coupled to the arm by a rack-and-pinion gear arrangement, or is coupled to the arm by a ball screw and nut system. The second axis of rotation of the arm preferably is perpendicular to the first axis of rotation of the carrier, and the cam and follower preferably are such that the mold charge pick-up cup is oriented horizontally to receive a mold charge and oriented vertically to deposit the mold charge in the mold of the compression molding machine. A control valve preferably is carried for selective application of vacuum and air under pressure through a passage in the arm to the mold charge pick-up cup to assist in transport and deposit of the mold charge into the mold.